1. Field of the Invention
The present invention relates in general to a navigation system, more particularly, to a navigation system and an operating method thereof, in which the navigation system shows the configuration of a complicated intersection a driver is about to enter, and displays where to turn and a progression rate of the car on the path the driver is headed to.
2. Discussion of the Background Art
In general, a navigation system marks on a map displayed on a screen a present position of a moving object that is calculated on the basis of information received from a Global Positioning System satellite (hereinafter, it is referred to as ‘GPS’).
Also, the navigation system provides a driver with any kind of information the driver needs for travelling, such as, travelling direction of the moving object, distance to a destination, present driving speed of the moving object, a path to the destination set by the driver before he takes off, and an optimal path to the destination.
A navigation system or GPS is widely used in various kinds of moving objects including ships, aircraft, or cars, and confirms a present position and a travelling speed of the moving object or determines a travelling path.
Particularly, a navigation system calculates the present position of the moving object on the basis of radio waves (or signals) indicating latitude, longitude, and altitude of the moving object provided from a plurality of GPS satellites. After that, a navigation system provides map information including the present position of the moving object to the driver with visual or voice guidance.
Therefore, a full navigation system is a route guidance system that calculates a present position of a car on the basis of information received from GPS and marks the present position of the car on a map or a screen.
A full navigation system also provides a driver with any kind of information the driver needs for travelling, such as, travelling direction of the moving object, distance to a destination, present driving speed of the moving object, a path to the destination set by the driver before he takes off, and an optimal path to the destination.
FIG. 1 is a diagram illustrating a configuration of a related art navigation system.
Referring to FIG. 1, a GPS receiver 102 receives position data transmitted from a plurality of GPS satellites 100 over an antenna, and a velocity sensor/Gyro sensor 104 detects rotation angle and velocity of the car.
An input unit 106 is a user interface where a user inputs any kind of key signal or sets a travelling path he wants to take.
A map data memory 108 stores map data and other additional information data. A CD-ROM (Compact Disk-Read Only Memory) is generally used as the map data memory 108.
A controller 110 controls general operations of the navigation system. To this end, the controller 110 determines a present position of a moving object on the basis of signals received from the GPS receiver 102, and matches the determined present position of the moving object on the map data stored in the map data memory 108.
When the user inputs a starting point and a destination through the input unit 106, the controller 110 searches a travelling path from the present position of the moving object to the destination, referring to the map data stored in the map data memory 108. Then the controller 110, through a display driving unit 112, makes a display 114 show the searched travelling path on a digital map.
A voice guidance unit 116 generates a voice through a speaker 118, guiding the driver of the moving object to the travelling path. However, this voice guidance is not absolutely required for the above described navigation system.
In short, the navigation system receives GPS satellite signals from a plurality of GPS satellites 100 located around the earth, and tracks down the trace of a car by detecting a travelling direction of the car.
Further, the navigation system provides the driver of the car with a shortest path from the starting point to the destination.
However, drivers who are not good at map reading or who cannot read the digital map fast enough often feel inconvenient to use the related art full navigation system because it only marks the present position of the car on the digital map displayed on the screen and does not provide any other tools to recognize the marked position.
Also, the complicated operational method thereof adds another inconvenience to drivers because it sometimes disturbs the drivers' concentration on driving, and it can end with car accidents.
To resolve the above problems, a Turn-By-Turn (hereinafter referred to as ‘TBT’) navigation system is now on the market. The TBT navigation system, unlike the full navigation system, uses an arrow to indicate in which direction the driver need to go.
Needless to say, the most fundamental yet essential function in a GUID (Graphic User Interface) of the TBT navigation system is a direction arrow.
FIG. 2 illustrates one embodiment of a traffic information service system, in which a portable terminal displays guidance for an intersection, i.e. in which direction a car should turn, by using an arrow.
To get the service shown in FIG. 2, a user should access to a wireless Internet by operating his portable terminal and choose ‘Traffic information service’. After that, he should input a destination he wants to go to. Then, the traffic information service system displays useful traffic information on an LCD of the portable terminal leading to the destination by using a direction arrow.
Referring to FIG. 2, on the top end of the LCD 200 of the portable terminal is the name of an intersection (e.g., First insurance intersection 210), and at the central portion of the LCD 200 is a left turn directional arrow 220 for the intersection. Also, three displays are on the right side of the directional arrow 220: a distance display 230 that tells how long a distance is left to the junction of the intersection, another distance display 240 that tells how long a distance is left to the user's desired destination, and a time display 250 that tells an amount of time left to get to the destination. At the bottom portion of the LCD 200 is a road name display 260, and a GPS receiving availability display 270 which indicates whether or not GPS signals can be received.
However, a problem with using an arrow for guiding in intersections to the destination is that a driver can be easily confused at which road he has to turn when being in an intersection because the directional arrow image does not always coincide with a real road.
Moreover, in case of a complicated intersection that is usually composed of several nodes and links and which cannot be indicated by one single node, it is hard to show the complicated intersection simply by using a left/right turn directional arrow.
What happens when the left/right turn directional arrow is applied to every node of a complicated intersection is that the driver (or the user) can be confused at the ever fast changing arrow.
Even though the directional arrow could be used only once at a complicated intersection, a driver needing to enter a complicated intersection larger and more complex than general intersections will still be more confused, not knowing where to turn.
In the past years, navigation systems have been used to perform route guidance by using arrow images, e.g., straight, left turn, right turn, and U-turn. This method has not been effective for real situations because in many intersections the roads are connected to each other in diverse angles.
Especially, when roads connected to an intersection are very near, the directional arrow image is rather confusing to the driver, only leaving the driver without finding into which road he should turn.
FIG. 3A through FIG. 3C illustrate usage of a directional arrow to a destination path when the intersection configuration is complicated, according to a related art TBT navigation system.
FIG. 3A illustrates a simple configuration of the real intersection seen from an entrance road of a car, in which intersection the entrance road is connected to several other roads.
As shown in FIG. 3A, the other roads are connected to the intersection in diverse angles. Particularly, an exit road is very densely located to the next roads.
Therefore, what most possibly happens when the related art TBT navigation system performs route guidance simply by using arrow images, i.e. straight, left turn, right turn, and U-turn, as shown in FIG. 3B, is that the driver misses the path he should take and goes to an adjacent road instead because there is a big difference between the arrow image direction and the direction of the actual exit road he should go.
For instance, referring back to FIG. 3A, a total of four roads are connected to the entrance road in different directions.
Here, the heading-up road is located on 210 degrees counterclockwise from the entrance road.
In such a case, a traditional navigation system provides the driver with a left turn arrow image similar to the one shown in FIG. 3B. However, comparing FIG. 3B with FIG. 3A, it is evident that the left turn arrow image is much different from the actual configuration of the roads, and thus, the driver can be confused in the intersection, not knowing where to turn.
Although the related art TBT navigation system stores a variety of different shapes of arrow images for guidance, there still is a limitation on its guidance in the intersections due to the technical features of the information terminal for the vehicle. Hence, the TBT navigation system could not provide an accurate arrow image for every intersection in real life.
Moreover, storing more than one arrow image for guidance and displaying the arrow images to the driver consumes too much memory of the TBT navigation system, even though it is done as an aid of the driver.
On the other hand, as shown in FIG. 3C, an arrow image can be flexible enough to set a free angle. However, if the roads connected to the entrance road are densely built up and the driver gets only the arrow for guidance, it is not easy to distinguish the exit road from the other roads of the intersection.
Another problem in the related art TBT navigation system is that it does not indicate a progression rate of the car entering to the complicated intersection. Thus, there is no way the driver can find out if he is actually entering the exit road as he intended.